There were rumors that Qt wanted to take the project proprietary. They didn't go through with those plans, but right now they are delaying all patch releases of Qt5 by 12 months, forcing KDE to maintain their own set of backported patches )https://invent.kde.org/qt/qt/qtbase/-/tree/kde/5.15), and rebase on top of Qt 5.15.3 and .4 etc. every so often, until KDE eventually ports to Qt 6.